Variometer



April 2s, 192s. 1,535,364

R. w. cAMFlELD ET Au.`

VARIOMETER Fil'd Feb. 7', 1925 Ililli /6 30 321 3l /8 F|E.3.

' ATTORNEYS.

r be varied.

Patented Apr. Z8, 1925.

UNITED STATES PATENT GFFICE.

RUSSELL W. CAMFIELD, OF BERKELEY, AND ERNEST G. DANIELSON, OF SAN FRANCISCO, CALIFORNIA.

VARIOMETER.

Application filed February 7, 1923.

EnNnsT G. DANinLsoN, a citizen of the United States, and a resident of the city and county of San Francisco, in the State of California, have invented a new and useful Variometer, of which the following is a specification.

This invention relates to an inductance coil having relatively movable coil portions, whereby the total inductance of the coil may Such an instrumentality is usually termed a variometer and is extensively used in connection with radio signaling.

It is one of the object of our invention to improve in general the mechanical features of such a device whereby it may be more reliable in service and neater in appearance.

Variometers are usually provided with two substantially equal coils concentrically disposed and connected in series, that are relatively rotatable so that they may gradually be adjusted from a position where they are cumulative to the maximum decree, to one where they oppose each other to a maximum degree. This movement is rendered possible by providing an axis of rotation for the rotor coil substantially at right angles to the axis of both coil windings. The connections for the circuit must of course be provided between the rotor coil and the stator coil, but as hitherto arranged these connections have had disadvantages, suoli as being the cause of interfering noises, or else they were liable to work loose or break olf. Itis thus another object of our invention to provide an improved form of circuit connection between the relatively movable coils.

Our invention possesses other advantageous features, some of which with the foregoing, will be set forth at length in the following description, where we shall outline in full that form of the invention which we have selected for illustration in the drawings accompanying and forming part of the preseut specification. Although we have shown in the drawings but one embodiment of our invention, we do not desire to be limited thereto, since the invention as expressed in the claims may be embodied in other forms also.

Serial No. 617,458.

Referring to the drawings:

Figure 1 is a front view of a variometer embodying our invention;

Fig. 2 is a view taken from the right hand side of Fig. 1 with rotor turned 30o;

Fig. 3 is a view of the variometer taken apart, with the rotor and stator elements opened up along a plane perpendicular to the axis of rotation of the rotor, and with certain other elements displaced slightly so as to show the construction of the parts in a clear manner;

Fig. t is a sectional view taken along plane 1-4: of Fig. 3; and

Fig. 5 is a sectional view taken along plane 5 5 of Fig. 3.

The stator coil 11 is in the present instance arranged external to the rotor coil 12, and is furthermore wound so as to provide substantially an internal spherical surface within which the spherically formed rotor` coil 12 may rotate, with a relatively small amount of clearance. In order to support this stator coil properly, we provide a pair of supports 13, preferably molded from insulating material. On the interior surfaces of these supports 13 the stator coil sections 11 are appropriately fastened, as by glue or the like, there being one coil section 11 for each of the supports 13. Projections 111, 15 from the sides of supports 18 serve conveniently not only to embrace the metal spacers 16, 17 but also to provide an anchor for the feet 18, upon which the entire variometer may rest. Bolts 19 serve to fasten the spacers 16, 17, the supports 13 and the feet 1S securely together. The two stator coil sections 11, as well as the supports 13, are in this way kept a slight distance apart in an axial direction, this separation corresponding to the thickness of the spacers 16, 17.

These spacers are in fact provided primarily for keeping the stator sections separated, whereby it is possible to provide ap propriate shafts for the rotation of the rotor coil 12. This coil 12 is likewise formed of two sections, wound on the rotor frames 2() that are preferably molded from insulating material. These frames 20 are adapted lo be fastened together, as by bolts 21, that pass through the integrally formed end covers 22 of the frames 20. Thus these frames 2O form a drum shaped figure with a spherical outside surface, and covers 22 correslionding to the' ieads of the drum. rhe rotor coil sections 12 are wound on the outer periphery of this drum, and are adapted, by proper rot-ation of the drum, to cooperate with the stator coils 11 for varying the total inducance of the device. The axis of rotation for the rotor 12 passes through the center vof spacers 16 and 17 as well as through the center of the stator and rotorcoils. Rotation of 180o of the rotor about this axis would cha-nge the inductance from a maximum to-a minimum. y

To the spacer 17 is rigidly fastened a shaft or pivot 28, which for this purpose is provided with a shoulder 2a and a stud portion projecting' through the spacer. A nut f 26 serves to clamp the shaft 23 securely to this spacer. lt is upon this shaft that the. rotor structure 12 is rotatably supported atv one side. For this purpose, the roto-r frames 2O are each provided with half-round depressions 27 which serve te embrace shaft 23 Awhen the two frames are fastened together. The shaftQB furthermoreserves to accommodate the connections between the rotor and stator in a neat andcompactinanner, and (in Order to accomplish this result, the. shaft is provided with an axial apertiue./Z8,.as welles a radial aperture 29 con municating therewith. The entire 'scheme of connections is apparent from a consideri.- tion of Fig. 3. Vl hat stator coil 1l which is associated with the lower frame 13 in Fig. 3, is connected, bya flexible lead 30to the outside diameter of shaft Q3, with tlm aid of a drop of solder. rlhis connection is madeclose to the spacer 1.7,'so that it may not interfere with the free rotation of the rotor .12 about shaft Continuing with the connections, a flexible lead or pigtail 31 is soldered to the shaft 23 where it projects into the hollow drum formed by members 20. rl`his connection leads to one of the rotor coils V12, which is connected, as by flexible lead 32,-with the other rotor coil. The insulated 'flexible lead from this rotor coil isA threaded through apertures QS-and 29 of shaft 23, and connects to that stator coil 11 which is associated with the upper frame 13 of 'Fig'. 3. evidentthat all of the stator and rotor coil sections are in series, each ofthe two stator A coil sections being disposed at the ends, and

both of the rotor coils beingarranged bctween vthese tworstator sections. Leads 3stand 35 from the stator coils may connect to appropriate binding' posts 36 whereby the variometer may be placed in any desired circuit.

lt is to benoted that the pigtail connec- From the` foregoing, it isY `further to be noted that the leads 31 and cannot be adversely affected by the turning ofrotor 22,sincefthey have a length of considerable extent over which the angular twist is distributed. This effect is due in a measure to the arrangement of these leads in the hollow pin 25, the lead 33 passing through the stationary radial aperture convenientlyv located in the gap formed between the spacer lr-and the outside surface of rotor 22; and lead 31 being anchored as by solder near the inner extremity Yof pin 25.

if' no limit be placed upon the relative angular movement between rotor and stator, there would be danger of the leads finally twisting ofi'. ln order to insure against suc-h an occurrence, we provide ai stop'that is incorporated with the shaft` 371 which is fastened tothe rotor Vaxially 1n line with shaft 23 and on the opposite side thereof. Y

Thisshaft isappropriately journaled in the spacer 16, and 1s held .witlunthe frames 2O Aof the rotor against relative rotationrtherewith, as by the aid Vofa pinSS passing through `the shaft and fitting intothe depressions .39' formed for it in these frames.,V The. projecting end #l0 ofthe shaft 3i"- serves as aconvenient means foi-adjusting the-'position of the rotor. The stop for the vrotor comprises a pin :4-1 fastened to shaft 37, and arranged to play in a groove '-l), formed in the projection V1-1 of onlyoue of the stator frames 13. rthe pin l1 .therefore permits only about 1800 of movementof theshaft 3T, forfbeyond that value this pin a-buts against that portion of the inner `wall of a projection 14 which falls opposite the groove i-2. ln this way a slot or groove isV Y'formed that extends-.only for a limitedfangle within which the stop pin llfmayplay.

TWe .arrange matters in such va. way as to prevent relative axial movement between the pivotshaft 23 and the irotor. frame, as well Yas to provide for a. slight frietional resistance to the turning of the rotor, whereby it vmay be maintained in anadjusted position. For this purpose a grooves/t3 is out in theshaft 23, with which cooperate Vone or more leaf springs tl, shown most clearly in Fig. l. These springs are' conveniently disposed in pockets l5 formed in the frames 20, and press resiliently against the lgroove 4:3.

' The shoulders 4G ofthe groove prevent relative axial movement between the springs A and the shaft 23,-andaat the same time-sum'- cient frictional force is developed-between the `springs and the shaft to maintain the rotor in any adjusted position.

We claim:

l. In a variable inductor, a stationary coil structure, a rota-table coil structure within the stationary structure, and means for rotatably supporting 4said rotatable coil and for leading connections thereto, comprising a hollow pivot pin for said rotatable coil, fastened to the stationary coil and projecting radially inwardly into the rotating structure, said pin having an aperture communicating with the interior hollow space, and opening to the space formed between the rotary structure and the stationary structure, and a` lead from one terminal ot the rotary eoil passing through the hollow pin and said aperture.

2. In a variable inductor, a pair of hollow shells, spacers between said shells, said shells serving to deline an interior spherical sui'- faee, a stationary coil supported on said surface, a rotary coil structure within the shell, and means for rotatably supporting said rotatable coil and for leading connections thereto, comprising a hollow pivot pin fas` tened to one of the spacers and extending` inwardly into the rotary structure, said pin having an aperture communicating with the interior hollow space, and opening to the space formed between the spacer and the rotary structure, and a lead from one terminal of the rotary coil, passing through the hollow pin and said aperture.

3. In con'lbination, a stationary structure, a rotatable coil structure, a pivot pin tastened to one of the structures and relatively rotatable with the other, and a flat spring carried by the. structure that i-s rotatable on the pin for producing a frictional resistance to relative movement of the two structures.

4. In combination, a stationary structure, a rotatable coil structure, a pivot pin fastened to one of said structures and relatively rotatable with the other, said pin having a. groove formed therein, and a flat spring litting within the groove, carried by the structure within which the pin has relative movement, wherebya rietional resistance is produced against relative movement ot' the two structures.

In combination, a stationary structure, al pivot pin fastened to said structure, a rotatable coil structure pivoted on said pin and formed of separable frames which are adapted to embrace the pin, said pin having a groove formed therein, and a resilient mein` ber held in a pocket between the separable :trames for contacting with the groove, whereby a trictional resistance is produced against relative movement of the two struetures.

In testimony whereof, we have hereunto set our hands.

RUSSELL XV. CAMFIELD. E. G. DANIELSON. 

